Fixed 2 blade vs 3 blade on sailboat

[wipe_out]

Our boat came with a fixed 3 blade prop probably fitted by the previous owner. The manual specified a two blade originally.
I understand the drag aspect of the 2 vs 3 blade prop but what other factors would influence the choice? Trying to understand the reasoning behind the previous owners decision to change it.

 

[LONG_KEELER]

In general terms, the 3 bladed prop would be better in terms of balance with more
grunt in reverse.

Two bladed prop would encounter less turbulent water to counteract lacking losing the third
blade and would bite more. Less drag too. Particularly handy for if you have dead wood in front of you to hide behind when sailing.

Let us know what boat you have as many here could assist you more.

Personally , I've mostly preferred two blades with slightly more blade area (turbine style)
but owned old boats that have enclosed prop apertures with deadwood north and south.

 

[neil_s]

Adding to LK's comment above - I think you get more grunt in ahead, too. 3 blade props are more efficient because they have more blade area. It comes down to what you want the boat to do best, motor or sail? If you have plenty of dosh, you could always get a folder!

 

[wipe_out]

LK, the. Oat is a Hunter (Legend) 326.

So the decision logic to me sounds like the previous owner was probably after better motoring performance.

We haven’t lived with it long enough yet so will see how it goes.

Neil_s. The folding/feathering options are a bit steep especially after all the other work we have done over the past year. ?

 

[oldharry]

3 blades present more surface area to the water, which is good when its driving the boat as it transfers power more efficiently. However that area has to be dragged through the water when sailing. If you have plenty of power in reserve for pushing the boat against heavy weather, then the two blader is the better option. However if you have a smaller engine which struggles to reach hull speed, then the 3 blader will make a significant difference when the going gets rough.

In reality, the slight extra drag is rarely significant for cruisers, but the gain in thrust when its really needed is.

 

[Graham376]

I changed from 2 blade fixed to 3 blade Featherstream. 3 blade gives us far better punch into wind and chop than 2. As it's feathering we also get less drag under sail but with a fixed one the opposite would be the case.

 

[jwilson]

After years of 3 blades on other boats I ended up with a two-blader on present boat: was initially suspicious about drive but it works very well indeed.

 

[eddystone]

I changed from 2 blade fixed to 3 blade Featherstream. 3 blade gives us far better punch into wind and chop than 2. As it's feathering we also get less drag under sail but with a fixed one the opposite would be the case.

+1